Line data    Source code

       1             : // Boost.Range library
       2             : //
       3             : //  Copyright Neil Groves 2014. Use, modification and
       4             : //  distribution is subject to the Boost Software License, Version
       5             : //  1.0. (See accompanying file LICENSE_1_0.txt or copy at
       6             : //  http://www.boost.org/LICENSE_1_0.txt)
       7             : //
       8             : // For more information, see http://www.boost.org/libs/range/
       9             : //
      10             : /**
      11             :  * Copyright Soramitsu Co., Ltd. All Rights Reserved.
      12             :  * SPDX-License-Identifier: Apache-2.0
      13             :  */
      14             : #ifndef BOOST_RANGE_DETAIL_DEFAULT_CONSTRUCTIBLE_UNARY_FN_HPP_INCLUDED
      15             : #define BOOST_RANGE_DETAIL_DEFAULT_CONSTRUCTIBLE_UNARY_FN_HPP_INCLUDED
      16             : 
      17             : #include <utility>
      18             : 
      19             : #include <boost/mpl/if.hpp>
      20             : #include <boost/optional/optional.hpp>
      21             : #include <boost/type_traits/has_trivial_constructor.hpp>
      22             : 
      23             : namespace boost {
      24             :   namespace range_detail {
      25             : 
      26             :     template <typename F, typename R>
      27             :     class default_constructible_unary_fn_wrapper {
      28             :      public:
      29             :       typedef R result_type;
      30             : 
      31             :       default_constructible_unary_fn_wrapper() {}
      32             :       default_constructible_unary_fn_wrapper(const F &source)
      33        1580 :           : m_impl(source) {}
      34             :       default_constructible_unary_fn_wrapper(
      35             :           const default_constructible_unary_fn_wrapper &source)
      36       47400 :           : m_impl(source.m_impl) {}
      37             :       default_constructible_unary_fn_wrapper &operator=(
      38             :           const default_constructible_unary_fn_wrapper &source) {
      39             :         if (source.m_impl) {
      40             :           // Lambda are not copy/move assignable.
      41             :           m_impl.emplace(*source.m_impl);
      42             :         } else {
      43             :           m_impl.reset();
      44             :         }
      45             :         return *this;
      46             :       }
      47             :       template <typename Arg>
      48             :       R operator()(Arg &&arg) const {
      49        1570 :         BOOST_ASSERT(m_impl);
      50        1570 :         return (*m_impl)(std::forward<Arg>(arg));
      51           0 :       }
      52             : 
      53             :      private:
      54             :       boost::optional<F> m_impl;
      55             :     };
      56             : 
      57             :     template <typename F, typename R>
      58             :     struct default_constructible_unary_fn_gen {
      59             :       typedef typename boost::mpl::if_<
      60             :           boost::has_trivial_default_constructor<F>,
      61             :           F,
      62             :           default_constructible_unary_fn_wrapper<F, R> >::type type;
      63             :     };
      64             : 
      65             :   }  // namespace range_detail
      66             : }  // namespace boost
      67             : 
      68             : #endif  // include guard